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A physical quantity $$X$$ depends on the velocity of light ($$c$$), Planck's constant ($$h$$), and Newton's gravitational constant ($$G$$) such that the dimensional formula of $$X$$ is identical to that of surface tension. If the relation is expressed as $$X = c^a h^b G^c$$, then find the absolute integer value of $$(a + 2b + 3c)$$.
Correct Answer: 0
The dimensional formula of surface tension is $$[\text{surface\ tension}]=\frac{[\text{force}]}{[\text{length}]}$$
Therefore, $$[\text{surface\ tension}]=MLT^{-2}L^{-1}=MT^{-2}$$
Given, $$X=c^ah^bG^c$$
The dimensions of the quantities are
$$[c]=LT^{-1}$$
$$[h]=ML^2T^{-1}$$
$$[G]=M^{-1}L^3T^{-2}$$
Hence, $$[X]=(LT^{-1})^a(ML^2T^{-1})^b(M^{-1}L^3T^{-2})^c$$
Comparing the powers of $$M,L,T$$ with $$MT^{-2}$$,
$$b-c=1$$
$$a+2b+3c=0$$
$$a+b+2c=2$$
The quantity asked is $$a+2b+3c$$
From the dimensional equation itself, $$a+2b+3c=0$$
Hence, the correct answer is 0.
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